Domestic Solar Heating System Research Articles

Techno-economic feasibility of various types of solar collectors for solar water heating systems in hot and semi-arid climates: A case study

The pursuit for sustainability and a reduction in reliance on non-renewable energy sources has fueled the growing use of solar energy systems worldwide. This study assesses the feasibility of using domestic solar heating systems in Kirkuk, Iraq. The study utilized T*SOL software focused on three different solar collector systems: Thermital, Eraslan, and Apricus, chosen based on their type of collector loop (open loop or closed loop), type of collector (flat plate or evacuated tube), and collector size. The impact of varying the size of the hot water storage tank was also analyzed. The aim was to find a cost-effective solution that maximizes energy efficiency, reduces initial and maintenance costs, and cuts CO2 emissions. The results of the economic analysis showed that the energy demand for the case study was 1430 kWh. Both open loop and closed loop systems were found to achieve a solar fraction of 86% using evacuated tube collectors, but the open loop system required a smaller storage tank. The amount of CO2 emissions avoided was estimated to be between 689.5 and 1316 kg/year. The study concludes that domestic solar heating systems in Kirkuk, Iraq offer a sustainable and cost-effective energy solution, eliminating the need for an electrical water heater and resulting in substantial energy savings.

Domestic Solar Heating: Historical Development, System Description,Social Aspects, and Future Prospects

With the advancing technology, there are many well-developed domestic solar systems with two main categories: activeheating systems and passive heating systems. This paper focuses on a functional heating system which includes solarwater and air heating systems. The main physical principles are solar thermal energy and heat transfer, implementedon solar collectors and heat exchangers. As for the environmental aspect, domestic solar heating systems can reducegreenhouse emissions, alleviating global warming. Moreover, with the increasing demand for renewable energy due tothe rising awareness of environmental protection, the marketing size of solar energy has become larger. Solar heatingsystems have been a fast-growing technology in many countries over the last decade. Compared with other energy, theprice of solar energy is considered the cheapest, which can help consumers save around $5,000 with a payback time of 5years. Therefore, the solar heating market will expand in the future because of carbon emission reduction and increasingefficiency.

Mass flow rate optimization in solar heating systems based on a flat-plate solar collector: A case study

Little works considered the optimization of working fluids in solar systems. Engineers, designers and scientists are interested with the optimization problems, furthermore it is very important specially, for solar systems to improve the energetic behavior and increase their efficiencies as a conversion system of solar irradiance to a useful thermal power. According to the available literature, the criteria of optimization mainly relates to energetic and economic analysis (one of them or both). The analysis was based upon the maximum useful energy obtained from solar collector. Accordingly, the optimum mass flow rate was found aspires to infinity. The second analysis is based upon minimum cost of the unit of useful energy [$/W]. The optimum mass flow rate of solar air-heating flat-plate collector for the considered domestic solar heating system has been found 29 kg/h per square meters of solar collectors. This paper deals with a third criteria that is, the amount of the additional energy required to achieve the required task from the solar system by means of auxiliary heating system. In where both the outlet temperature and mass flow rate play crucial role in the heat exchange between the fluid in the collector loop and the fluid in the load loop.

The enhanced heat transfer of diathermic oil-based alumina-doped zinc oxide nanofluids for domestic solar heating systems

Doped material-based nanofluids, as an extension of single-phase nanofluids, expand the performance of heat transfer fluids. In this study, a new type of diathermic oil (DO)-based alumina-doped zinc oxide (AZO) nanofluids was prepared, and the thermophysical characteristics of nanofluids were analyzed. It could be found that the addition of new doped nanoparticles made up for the deficiency in the performance of DO as heat transfer fluid (HTF). Compared with the pure DO, the thermal conductivity of the AZO nanofluids (0.08 mass%) was increased by 8.125%. And the viscosity of nanofluids was decreased by 70% as the temperature increased. So as to further determine the application of nanofluids in the domestic heating system, the parameters of forced convection heat transfer in the tube were analyzed in this article. The convective heat transfer coefficient of AZO nanofluids increased with the increase in temperature. At 50 ℃, the convective heat transfer coefficient of 0.08 mass% AZO nanofluid reached the maximum of 5.49% compared with pure DO. More importantly, this research investigated the heat transfer benefits of using nanofluids in domestic solar heating systems. These promising results indicated that AZO nanofluids showed excellent properties at higher temperatures. It shows DO-based AZO nanofluids application potential in domestic solar heating systems.

Water-paraffin dispersion systems: manufacturing and application

The paper presents the study results of the stability and heat storage capacity of paraffin-in-water phase change suspensions (PCSs) obtained by the homogenization of paraffin and water in the developed rotary hydrodynamic homogenizer. The optimal concentration of components for obtaining stable paraffin-in-water suspensions is found. It is shown that the stable PCSs in the form of pastes, gels, and liquids can be obtained depending on the concentration of water, paraffin, and the surface active agent (SAA) as well as its type. In addition, the scheme of the solar heating system with the heat storage tank where the PCS functions both as the heat transfer fluid and the heat storage media is presented. It is shown that the use of PCS in the domestic solar heating system allowed the heat storage capacity of the storage tank to be increased by 25% as a result of the high fusion heat of paraffin and the high value of the water specific heat capacity. The estimation of the saving rate from applying fluid PCS as a heat storage medium is also presented and discussed.

Performance characteristics of a residential-type direct absorption solar collector using MWCNT nanofluid

In this study, the performance characteristics of a nanofluid-based direct absorption solar collector are investigated numerically and experimentally. The numerical model of nanofluid-based direct absorption solar collector was developed by solving radiative transfer equation combined with energy equation. The outlet temperature is analyzed by variation of internal emissivity of bottom wall, collector height, nanofluid volume fraction and flowrate. Then, a prototype of this new type of collector was built with applicability for domestic solar heating systems. As working fluid, different volume fractions of carboxyl functionalized multi wall carbon nanotubes in water and ethylene glycol mixture (70%:30% in volume) were prepared and their thermo-optical properties were presented. The procedure of EN 12975-2 standard was used for testing the thermal performance of the collector. The tests were performed in different flowrates from 54 to 90 l/h (0.015–0.025 kg/s) and two different internal surfaces (black and reflective) of bottom wall. By comparison of calculated and measured collector efficiencies for different volume fractions, it was shown that the numerical model was accurate within ±5% of the experimental results. The collector efficiency is increased by increasing nanofluid volume fraction and flowrates. The nanofluids improve the collector efficiency by 10–29% than the base fluid. The results of the study confirm that this new kind of collector can be best utilized in solar water heating applications.

The Effect of Measurement Uncertainty and Environment on Domestic Solar Water Heating Systems’ Energy Efficiency Grades

Abstract In China, two important national standards were implemented on Aug 1st, 2012, one is ‘Specification of domestic solar water heating systems’ (GB/T 19141-2011), the other is ‘Minimum allowable values of energy efficiency and energy efficiency grades for domestic solar water heating systems’ (GB 26969-2011). According to these two standards, the energy efficiency grades indicator CTP (coefficient of thermal performance) should be tested and calculated by daily useful energy and average heat loss factor of domestic solar heating system. Through experiment and calculation, the effect of measurement uncertainty and daily average ambient temperature on the migration of domestic solar water heating systems’ (DSWHS) energy efficiency grades was discussed. The calculation and analysis methods may be helpful for data consistency co-verfication between different inspection organizations.

Transient Thermal Behavior of a Vertical Solar Storage Tank with a Mantle Heat Exchanger During No-Flow Operation

Transient thermal behavior of a vertical storage tank of a domestic solar heating system with a mantle heat exchanger has been investigated numerically in the charging mode. It is assumed that the tank is initially filled with uniform cold water. At an instant of time, the hot fluid from collector outlet is uniformly injected in the upper section of the mantle heat exchanger and after heat transfer with the fluid inside the tank, withdrawn from the bottom part of the heat exchanger. The conservation equations in the cylindrical coordinate and in axis-symmetric condition have been used according to the geometry under investigation. Governing equations have been discretized by employing the finite volume method and the SIMPLER algorithm has been used for coupling between momentum and pressure equations. The Low Reynolds Number (LRN) ω − k model is utilized for treating turbulence in the fluid. First, the transient thermal behavior of heat storage tank and the process of formation of thermal stratification in the heat storage tank were investigated. Then, the influence of Rayleigh number in the heat storage tank, Reynolds number in the mantle heat exchanger and vertical positioning of mantle on the flow and thermal fields and the formation of the thermal stratification was investigated. It is found that for higher values of Rayleigh number, a more suitable thermal stratification is established inside the tank. Also it is noticed that increasing the incoming fluid velocity through the mantle heat exchanger causes a faster formation of the thermal stratification. A superior thermal performance was achieved when the mantle heat exchanger is positioned at the middle height of the storage tank.

A thermo-economical optimization of a domestic solar heating plant with seasonal storage

In this study, the thermo-economic optimization analysis to determinate economically optimal dimensions of collector area and storage volume in domestic solar heating systems with seasonal storage is presented. For this purpose, a formulation based on the simplified P 1 and P 2 method is developed and solved by using MATLAB optimization Toolbox for five climatically different locations of Turkey. The results showed that the required optimum collector area in Adana (37 °N) for reaching maximum savings is 36 m 2/house and 65 m 2/house in Erzurum (39 °N) for same storage volume (1000 m 3). The effects of collector efficiency on solar fraction and savings are investigated. The simulation results showed that the solar fraction and savings of the selective flat plate collector systems are higher than the other black paint flat plate collector systems.

98/00662 A computational model of a domestic solar heating system with underground spherical thermal storage

98/00662 A computational model of a domestic solar heating system with underground spherical thermal storage

A computational model of a domestic solar heating system with underground spherical thermal storage

This theoretical study deals with a domestic heating system assisted by solar energy stored in an underground spherical container. The system includes a heat pump. The analytical model employed calculates the water temperature in the storage vessel, as well as the temperature distribution in the surrounding geological structure, by using the monthly-average solar radiation and ambient temperature. Storage temperature, collector efficiency, performance coefficient of the heat pump (COP) and annual solar fraction are computed and presented in various graphs. The importance of seasonal solar energy storing in the ground is demonstrated.